According to one of the known methods of potassium pulp processing (Russian Federation Patent # 2132397 RF, MPK S 22 V7/00, published on Jun. 6, 1999), gold-containing pulp is cleaned of salts, after which the salt water formed during cleaning is removed and replaced by fresh water, and the final pulp is chlorinated by chlorine gas while care is taken to ensure that active chlorine content in leaching solution is maintained within 0.3-2.0 g/l. After the leaching, the process is completed, gold is recovered by a sorption method.
The disadvantages of the above method include the need to thoroughly clean the chlorides and use elemental chlorine, a high toxic substance, for gold recovery.
According to another known method of processing of clay-salt pulp at salt chloride production facilities (Russian Federation Patent # 2208058 RF, MPK S 22 V11/00, 7/00, published on Jul. 10, 2003), slimes are cleaned of chlorides until residual chlorine content is within 3-7%, after which the cleaned pulp undergoes concentration, drying, agglomeration and continuous heat-treatment at up to 1000-1150° C. while the content of oxygen in heat-treatment gas is maintained within 13-16%, until the final material is produced with maximum chlorine content of 0.3%. The gaseous phase of the heat treatment process is treated by cooling, condensation and absorption cleaning, which includes the recovery of condensates of solid-state chlorides and absorption pulp, and further sorption of gold and silver from pulp.
The disadvantages of the above method are as follows:                1) High power inputs due to conducting of the roasting process at 1000-1150° C.        2) The process of sublimation of gold and silver chlorides at oxidizing conditions does not affect platinoids, and they (platinoids) continue to remain in the cinder.        3) Catching of gold and silver sublimates is complicated and inefficient due to low content of gold and silver in the gaseous phase.        
From the technical viewpoint, the closest to the instant invention is the method for precious metal recovery from a concentrate produced from clay-salt residues (slimes) of potassium production (Russian Federation Patent # 2235140, MPK S22V 11/00, published on Aug. 27, 2004], which includes the oxidizing roasting of the concentrate and cinder acid-leaching, wherein prior to the roasting of the concentrate is mixed up with sodium chloride and pyrite at 1:(0.1-0.2):(0.1-0.2) ratio. The oxidizing roasting of the fusion mixture is carried out at 450-600° C. for 1-5 hours, whereas the cinder leaching is achieved by using a diluted hydrochloric or sulphuric acid, and transferring of gold and platinum metals to the solution.
The disadvantages of the above method include insufficient precious metal recovery ratio and high power input in the process.